WASHINGTON — The former chief of the federal government’s information-sharing program said Friday that preliminary signs indicate law enforcement and intelligence agencies failed to properly scrutinize one of the Boston Marathon bombing suspects after he was added to a terror watchlist by the CIA months after FBI investigators concluded he did not pose a threat.

Ambassador Thomas E. “Ted” McNamara said in an interview that the fact that Tamerlan Tsarnaev had been placed on a terror watchlist by the CIA should have triggered more alarms among counterterrorism officials, especially after he traveled to a known hotbed of Islamic militancy in Russia, Dagestan, in 2012.

“This looks like a mistake in the sense there should have been some method to jack up his significance,” said McNamara, who served until 2009 as the Program Manager for Information Sharing Environment, a position established in the wake of 9/11 to make sure counterterrorism agencies share information on potential threats. The ISE office reports to the director of national intelligence, which also was created after the 2001 attacks.

“This guy was considered a low-level threat,” he added. “There are a few things that might have bounced that up to higher level attention. But apparently it stayed in that low-level database.”

At Russia’s request, Tsarnaev was first investigated by the FBI between March and June of 2011. The FBI determined he did not pose a threat. The FBI has said that it sought additional information from Russia on Tsarnaev on repeated occasions but received no response.

In September 2011, after a similar request by the Russians to the CIA, the CIA requested that Tsarnaev be placed on a terror watch list, and he was placed on the list the National Counter-Terrorism Center, set up after 9/11 to coordinate the different databaes.

Tsarnaev’s name also was placed on a separate FBI terrorist screening database, and another one linked to the Department of Homeland Security.

Homeland Security detected that his travel to Russia in 2012, but his warning status was not high enough to require an follow-up interview by border authorities when he returned. A security official said this week the FBI’s Joint Terrorism Task Force in Boston was notified of his travels, however.

Meanwhile, Massachusetts officials who oversee antiterrorism “fusion centers” created to disseminate federal, state, and local information on potential terrorist threats said they were never informed about the FBI’s original three-month investigation.

McNamara views this story as a trail of missed opportunities to identify an increasingly radicalized subject.

“We have come an incredibly long way but we still have a substantial way to go,” said McNamara, who also served as ambassador-at-large for counter-terrorism as the State Department. “We sometimes forget that we are not as fully up to speed as we ought to be or need to be.”

McNamara’s expressed his concerns Friday as the House Foreign Affairs Committee heard testimony from specialists on the North Caucuses region of Russia, which encompasses Chechnya and Dagestan. Tsarnaev, a citizen of Kyrgyzstan who died after a firefight with police in Watertown on April 19, was planning during 2011 to travel to Dagestan, which prompted Russia’s Federal Security Service to warn the FBI and CIA that he had become radicalized.

In response to questioning from Representative Bill Keating, a Cape Cod Democrat, specialists suggested that continuing distrust between former Cold War foes may have contributed to the failure to track Tsarnaev.

“This is the problem of distrust between our countries and our security forces,” said Andranik Migranyan, director of the Institute for Democracy and Cooperation in New York and a former adviser to the Russian government.

He said he believes US officials may have doubted the Russians motives in passing along information about Tsarnaev.

“I am afraid that they just didn’t pay enough attention to this warning,” he added, speculating the US officials suspected Russia’s overture was “some Russian plot — ‘This is not [a] terrorist, it is something else.’ ”

Keating, a member of both the Homeland Security and Foreign Affairs Committees, said he hopes that one lesson from the Boston tragedy is that the two countries need to find a way to work together more closely on these matters.

“One of things we want perhaps to come of this is a better opportunity to have security advisers and law enforcement that work more closely, despite our differences, as difficult as they can be at times,” Keating said. “In both countries, lives could be lost.”